Production of close woven cellulose fabrics by dissolving terylene support yarn



Patented Aug. 19, 1952 v PRODUCTION OF CLOSE WOVEN CELLULOSE FABRICS BYDISSOLVING TERYLENE SUP- PORT YARN Bertram Pusey Ridge, Potters Bar,England, assignor to Imperial Chemical Industries Limited, a corporationof Great Britain 'No Drawing. Application March 8, 1949, Serial No.80,331. In Great Britain March 17, 1948 This case relates to theproduction of improved fabrics from cotton, regenerated cellulose orother alkali resistant yarn, as hereinafter defined, and particularly tothe production of fabrics from twistless alkali resistant yarn.

*Britishs'pecification 550,525 relates to a process for the productionof fabric from yarnconsisting wholly or partlyof soluble alginic' fibresand thereafter modifying the fabrics by dissolving or gelatinising someor all of the alginic fibres. "The process described suffers fromthe'clisadvantage that alginic yarns possess only low tenacity. Whenthis process is applied to the production of fabrics from twistlessyarns e. g. cotton yarns, this disadvantage is particularly marked.Yarns for use in the making up of such fabrics are composite yarnswherein the twistless cotton yarn is strengthened by the alginic yarnbeing twisted round the twistless yarn and acting as asupporting'thread. Because of the low tenacity of the alginic yarn, thespinning operation whereby the twistless yarn and the alginic supportingthread are brought together, must be conducted at a relatively slowspeed otherwise breakages occur. Furthermore to obtain a composite yarnstrong enough to withstand the tensions used in normal weavingoperations it is necessary to use an alginic yarn or filament ofrelatively heavy denier, e. g. 100. The removal of such a yarn orfilament from the composite fabric leaves a loosely packed .fabric. Afurther disadvantage is the large quan tity of alginic yarn or filamentwhich is dissolved away and the resultant high cost of such a process.

Fabrics produced from twistless yarn have many excellent.characteristics. For example, they have a soft hand, warmth withoutbulkiness, a silky appearance and lustre and high strength. Diflicultyis however experienced in producing close packed fabrics from theseyarns by the methods of the prior art.

The use of an easily removable yarn in the production of fabric alsomakes possible the production of decorative effects in the fabric, Theremovable yarn may, for example, be introduced in the form of a patternand partially or wholly dissolved away as desired. It will beappreciated that there are many possible variations in the manner inwhich the fabrics, or the yarnsused in the fabrics, may be made up toprovide a great variety of original decorative fabrics.

An object of the present invention is the production of new and improvedfabrics from alkaliresistant yarns. A further object is the productionof an improved fabric from twistless alkali v 2 Claims. (Cl. 8-114.6)

resistant yarn. A further object is the production of a close packedfabric from twistless alkali resistant yarns. A still further object isthe provision of a process whereby fabric composed of twistless alkaliresistant yarn may be produced more easily and more cheaply than by themethods of the prior art. Yet a further object is the production ofdecorative-effects in fabrics comprising alkali resistant yarns.

According to the present invention these objects are accomplished by aprocess wherein fabrics com-prising alkali resistant yarn and yarncomposed of a highly polymerised polymethylene terephthalate, whereinthe polymethylene group contains from 2 to 10 carbon atoms inclusive,are treated with caustic soda solution to remove at least some of thehighly polymerised polymethylene terephthalate yarn.

In a preferred form of the invention the alkali resistant yarn is atwistless yarn and is supported by the highly polymerised polymethyleneter ephthalate yarn during the manufacture of the fabric. The twistlessyarn may be supported by twisting the highly polymeric linear ester yarnor filament round the twistless yarn or by any other means known in theart.

Alkali resistant yarns include cotton and regenerated cellulose.

The production of the highly polymerised polymethylene terephthalates isdescribed and claimed in British specifications 578,079 and 590,451.These highly polymeric linear esters may be 'melt spun into filamentshaving tenacities of the order of 5 to 8.5 gms. per denier. Thus it ispossible to obtain a filament or yarn of the specified polyester whichis very fine e. g. 10-15 denier and yet has sufficient strength tosupport the twistless yarn during the spinning of the composite yarn andalso to support the yarn during the production of fabrics from thesecomposite yarns. The polymeric esters from which the supporting threadsare made give threads of high tenacity which are much stronger than thealginic yarns previously used. In the production of composite yarns foruse in the production of fabrics from twistless yarn this high tenacityenables the spinning of the composite yarns to be carried out at speedsconsiderably higher than those previously used without undue breakage.This'increase in the production rate enables the yarns and thus thefabrics made therefrom to be produced more cheaply than was formerlypossible. I

The process of the present invention is applicable to fabrics made up ofany alkali resistant 60 lbs. per sq. in. gauge, for times up to 8 hours.y

We have found that such a treatment is sufiicient to remove all thethreads of the highly polymeric} polymethylene terephthalate if desired.As an alternative to pressure boiling the terephthalate yarn present inthe fabric may be skinned down to any desirable extent, or if necessaryremoved completely by treating the composite fabric at atmosphericpressure on a jigger or winch machine, or even by steeping ina vatywitha 4% solution of caustic soda at a temperature near to the boil.Treatments of this sort are again common practice with cotton goods. Bythe use of the process of thisinvention, therefore, cotton fabricscomposed of twistless yarn or with decorative effects may be producedwithout subjecting the woven, knitted or braided fabric to anyprocess-other than those normally used in the treatment of cottonfabric. I

V In the production of fabric from twistless yarn it is desirable to,.remove all the supporting threads. The twistless yarn with itsattendant supporting threads may be used in the warp or Weft but toobtain a fabric having all the advantages of a twistless yarn fabric thetWistless yarn and supporting thread must be used in both warp and weft.The supporting threads may be so fine because of their high strengththat it is possible to obtain a fabric which after the removal ofsupporting threads is close packed and has all the other desiredpropertiesof a twistless yarn fabric. The fact that such fine supportingthread can be used also reduces the cost of the fabrics considerably asthe amount of material dissolved out and discarded is not so great asthe amount lost using the methods of the prior art.

lfWhilethe process has been described particularlywith reference to theproduction of fabric from twistless yarn it will be appreciated howeasily the process may be applied to the production of decorativefabrics. The caustic soda treatment can remove some or all of the highlypolymeric polymethylene terephthalate yarns according to the severity ofthe treatment.

The following examples illustrate but do not limit the scope of ourinvention. Example 1 A 10 denier yarn of polyethylene terephthalate wastwistedrround a 1/30 cotton thread (equivalent in dimensions to 170denier thread) so that the thread remained twistless. This compositeyarn was then woven into a plain fabric. The resulting tightly wovenfabric was treated in a 2% solution of caustic soda at the boil at 40lbs. 7 pressure in an autoclave for one hour, then washed with water.All the polyethylene terephthalate yarn was dissolved and a fine, soft,warm fabric of high strength and silky appearance was obtained.

Example 2 A portion of the original fabric of Example 1 was treated inan open vessel containing a 4% solution of caustic soda at the boil. Theyarns of polyethylene terephthalate were removed after 7 hourstreatment.

4 Example 3 In the weaving of a cotton fabric from 1/30 cotton thread(equivalent in dimensions to 170 denier thread) polyethyleneterephthalate (20 denier) was introducedas"alternate weft threads over aportion of-the fabric. O'n treating'the fabric as in Example 2 thepolyethylene terephthalate yarns were dissolved and a fabric with astripe of more loosely woven material resulted.

' Example 4 The original fabric of Example 3 was treated in an open bath.of.4% caustic soda solution for 4' hours only, at the boil. Theresultant fabric had a stripe of material where some of the weft yarnswere finer than others, i. e. where the poly- .ethylene terephthalateyarns had been partially dissolved.

It will be appreciated that the expression alkali-resistant yarns, asused in the foregoing description, does not necessarily mean yarns whichare totally insoluble in caustic soda solutions of all concentrations.The meaning which this terminology is intended to convey, as thoseskilled in the art will appreciate, is that-the yarns from which thefabrics are to be made'and which are themselves too weak to be wovenalone, are resistant, i. e., substantially unaffected or substantiallyinsolubleto the caustic soda solutions utilized to dissolve out thealkali-soluble, highly polymerized polymethylene terephthalate yarn.

Iclaim:

1. Aprocess for the production of irnproved fabric from a twistless yarnselected from the group consisting of cotton and regenerated cellu-.

lose yarns which comprises forming a composite yarn from said twistlessyarn and a yarn ofv a highly polymerized polymethylene terephthalatehaving from 2 to 10, inclusive, carbon atoms in the methylene group,producing a fabric from said composite yarn and thereafter dissolvingoutsaid polymethylene terephthalate yarn from said fabric by immersing saidfabric in an .8 to 4% solution of caustic soda under apressure of from 0to lbs. per square inch gauge for a time sufficient to dissolve saidterephthalate yarn up to eight hours, the conditions utilized in thedissolution of said terephthalate yarn being such as to leave saidtwistless yarn substantially unaifected.

2. The process of claim 1, wherein the polymethtylene terephthalate yarnis a polyethylene terephthalate yarn of 10 to 20 denier.

. BERTRAM PUSEY'RIDGER'I REFERENCES CITED The following. references areof'record in the file of this patent: 1 r

UNITED STATES PATENTS Number.

1. A PROCESS FOR THE PRODUCTION OF IMPROVED FABRIC FROM A TWISTLESS YARNSELECTED FROM THE GROUP CONSISTING OF COTTON AND REGENERATED CELLULOSEYARNS WHICH COMPRISES FORMING A COMPOSITE YARN FROM SAID TWISTLESS YARNAND A YARN OF A HIGHLY POLYMERIZED POLYMETHYLENE TEREPHTHALATE HAVINGFROM 2 TO 10, INCLUSIVE, CARBON ATOMS IN THE METHYLENE GROUP, PRODUCINGA FABRIC FROM SAID COMPOSITE YARN AND THEREAFTER DISSOLVING OUT SAIDPOLYMETHYLENE TEREPHTHALATE YARN FROM SAID FABRIC BY IMMERSING SAIDFABRIC IN AN .8 TO 4% SOLUTION OF CAUSTIC SODA UNDER A PRESSURE OF FROM0 TO 60 LBS. PER SQUARE INCH GAUGE FOR A TIME SUFICIENT TO DISSOLVE SAIDTEREPHTHALATE YARN UP TO EIGHT HOURS, THE CONDITIONS UTILIZED IN THEDISSOLUTION OF SAID TEREPHTHALATE YARN BEING SUCH AS TO LEAVE SAIDTWISTLESS YARN SUBSTANTIALLY UNAFFECTED.